Fuel shut-off mechanism



March 1, 1960 WENTWQRTH 2,926,892

FUEL SHUT-OFF MECHANISM Filed Dec. 3, 1956 IN VEN TOR.

A TTORNEY FUEL SHUT-OFF MECHANISM Joseph T. Wentworth, Royal Oak, Mich.,assignor tov General Motors Corporation, Detroit, Mich, a corporation ofDelaware The invention relates to a fuel shut-offmechanism and moreparticularly to a mechanism for interrupting the fuel supply to aninternal combustion engine in order to side of the shaft 14 andconnected through appropriate reduce the hydrocarbon emission by anautomotive engine during decelerationt It is well known that automotiveengines normally discharge appreciable quantities of unburned orpartially unburned fuel during deceleration when the intake manifoldvacuumis high. This high vacuum causes conditions to prevail in theengine combustion chamber that are not conducive to the completecombustion of the fuel and air mixture introduced. in

the chamber.

Various mechanisms have been proposed in the past which shut off thesupply of fuel to the combustion chamber of an engine duringdeceleration periods. These previous proposals have been operable topositively interrupt the fuel supply by means of a shut off valve orequivalent sealing devices. They have not been satisfactory in manycases due to the delay required in recharging the engine when thedeceleration period is over or thecomplexity of the machinery involved.

The invention presents a device which shuts off the fuel flow duringdeceleration by rotating the throttle plate orvalve past the idle jet.When the throttle plate is so rotated, the primary idle dischargepassage is upstream of the throttle plate. No vacuum exists at thispoint and no fuel will therefore flow in the idle circuit. When thedeceleration period is over, the throttle valve is returned to the idleposition and the accelerator pump will be caused to discharge fuel intothe manifold, thus quickly re'-establishing a normal supply of fuel. Theidle jet will then be downstream of the throttle valve and the vacuum inthat portion of the intake system will cause fuel to flow in the idlecircuit. t 9

t In the drawing:

Figure 1 shows a. segment of an intake for an internal combustion enginehaving a deceleration fuel shut-off mechanism embodying the invention,portions beingbroken away and in section.

Figure 2 shows a cross-section view of the throttle valve controlled bythe mechanism of Figure 1,the valve being in position relative to theidle jet.

The internal combustion engine on which the mech anis'm is installed isprovided with an intake duct 10 in which a throttle valve 12 is mountedon a rotatable shaft 14. The intake duct preferably has a substantiallycir-.

valv'e is in the idle position. A suitable device such as.

This difference indiameters elimi- 2,926,892 Patented Mar. 1, 1960throttle valve, such as in the intake manifold of the engine. The shaft14 preferably extends through the walls of duct 10 and beyond eitherside of the duct. A conventional throttle control arm 26 may be securedto one linkage 56 with accelerator pedal 58. The fuel shut-offmechanism, which is the subject of the invention, may be secured to theother end of the shaft 1 4 or at a point adjacent to the conventionalthrottle arm on the shaft. fuel shut-off control includes a-cam 24, athrottle control arm 26, an idle speed adjusting screw 28 and a camcontrol link 30. The throttle control arm 26 is non-rotatably secured toshaft 14 and may be provided with a hole 32 to which the acceleratorpump linkage 50 may be attached. Cam control link 30 may be connected toany positioning mechanism which is sensitive to conditions ofdeceleration in the engine- The vacuum sensitive mechanism 34 is shownby .way of example. Mechanism 34 includes housing 36 forming a vacuumchamber 38 and.

closed at one end by a diaphragm '40. The other side of the diaphragmforms a chamber 42 which may be opened to the atmosphere. A compressionspring 44 may be provided in vacuum chamber 38 to resist the vacuum inthe chamber and to return cam 24 to its idle position at the end ofadeceleration period. The vacuum in chamber 38 is transmitted throughline 22 to that cham- An adjustment mechanism may be her from theengine. provided in housing 36 which includes a first screw 46 foradjusting the tension on spring 44 and a second screw engine, cam 24 isrotated to the deceleration position D,

permitting adjusting screw 28 to move toward the center of cam 24. Thisallowable movement of screw28 permits the rotation of arm 26 and theconsequent rotation ofthrottle valve '12 to the deceleration position.

When the deceleration sensing mechanism 34 indicates that thedeceleration period is over, the idle return stop cam '24 will bereturned to the position I, forcing the .throttle plate 12 back to itsposition I through movement of adjusting screw 28 and arm 26. Intakevacuum will again be impressed upon the idle discharge jet 16 and themovement of the throttle linkage to the idle position will cause theaccelerator pump 52 to discharge fuel through passage 54 into themanifold and re-establish a normal supply of fuel to the engine. Thisfuel is injected when the manifold vacuum is at approximately theidling-value, thusminirnizing the jerk due to restarting the engine. Thethrottle valve 12 can be returned to idle position or any otheroperating position at any time by actuating the conventional throttlemechanism. The fuel shut-off mechanism therefore inno way hinders normalcontrolof the engine by the vehicle operator.

trol, etc. Since the vacuum in the intake manifold is on the order of 21to 26 inches of mercury during decel-. 1 eration, while normal idlevacuum doesfnot exceed 21 The nch of memo, th s e e ly igh vacuum obable only during acceleration provides an excellent control foractuating the deceleration fuel shut-off mechanism. This device willreduce the unburned hydrocarbon during deceleration by cutting off thefuel supply and will aid .in establishing a' smoother engine restartbyusing the accelerator pump-to aid in re-establishing fuel flow. The timefor v reestablishing fuel flow may be shortened to some extent byproperly locating the deceleration position of throttle valve 12relative to idle jetlso that fuelsupply is maintained at a pointimmediately adjacent the idlejet. By controlling the position of thethrottle valve relative to thevidle jet and utilizing the vacuum on therespective sides of the throttle valve, the throttle valve need not beso closelyvfitted to the intake duet thatit must completely seal thatduct,

' as has been required by \some fuel supply interrupting systemspreviously proposed. The difference in duct and throttle valve diameterspermits some intake air to flow through the manifold to the cylinders,drying the walls of the manifold quickly and preventing continued fuelcombustion over a long period of time after the fuel supply isinterrupted.

What is claimed is:

1. A fuel supply control mechanism for an internal combustion'engine,said .mechanism preventing the introduction of fuel into said engineonly during zero throttle engine deceleration periods andre.-establishing the supply of said fuel at the end of each of saidperiods and including an air intake duct having a throttle valve and anidle fuel discharge jet mounted therein, an accelerator pump havingmeans for discharging fuel into saidengine, means sensing said enginezero throttle deceleration periods and operatively connected with androtating said throttle valve to a first position downstream of said idlejet only during said periods to interrupt fuel flow from said jet, saidthrottle valve rotating means including biasing means returning saidthrottle valve to a second position upstream of said jet at the end ofeach of said periods to re-establish fuel fiow from said jet, and meansinterconnecting said throttle valve rotating means and said acceleratorpump for actuating said accelerator pump upon return of said throttlevalve to said second position whereby fuel is discharged into saidengine by (said pump.

2. The mechanism of claim 1, said throttle valve rotating meanscomprising throttle =valve accelerator linkage and'a motor and a camactuated by said motor and engagingsaid linkage at said first positionto permit said throttle valve rotation to said first position underinfluence of said accelerator linkage and engaging said linkage toreturn said throttle valve to said second position.

3. Means for preventing the emission of unburned hydrocarbons from aninternal combustion engine during zero'tlrottle deceleration periods,said means including a throttle valve and an idle fuel discharge jet andthrottle valve control mechanism including a throttle valve zerothrottle position limiting cam and means sensing said engine zerothrottle deceleration periods and connected with said cam to rotate saidcam to first and second positions, an accelerator pedal and linkagesconnecting .said pedal to said throttle valve-and engageable with saidcam, said valve being moved by said linkages relative to .said jetunder'control'of said accelerator pedal to be positioned upstream ofsaid jet and limited to the upstream positions by said cam in said camfirst position under all operating conditions except zero throttledeceleration and to be positioned downstream of said jet during zerothrottle deceleration conditions with said cam in said second position.a

a linkage po i on d lim ting said al e be n mo e able by said linkage toa first position at engine idle relative to said idle jet whereby saidjet is downstream of said valve and said valve is limited againstmovement from said position toward the zero throttle direction by saidcam engaging said linkage, and movable by said linkage to a secondposition and closed throttle deceleration whereby said jet is upstreamof saidvalve, said cam having actuating means connecting therewith andincluding means sensing said engine close'd'throttle decelerationperiods for moving said cam out of the first limiting position duringsaid closed throttle deceleration periods.

5. Throttle valve :control mechanism for an internal combustion enginehaving a throttle valve, said mechanism comprising a shaftsupporting'said valve, an arm non-rotatably secured to said shaft forimparting rotary movement thereto and having an idle position adjustingmember, a position controlling cam engageable by said member, and meansresponsive to throttle position and deceleration of the engine andconnected with said cam for positioning said cam to limit rotation ofsaid valve in one direction to a predetermined idle position in one camposition and to permit further rotation of said valve in said onedirection beyond said predetermined idle position,

during zero throttle deceleration of the engine.

6. The mechanism of claim 5,, said cam positioning means including amotor operatively connected with'the engine air intake and responsive toengine intakevacuurn.

7. Hydrocarbon combustion control mechanism for controlling fueldelivered to aninternal combustion'enginc, said mechanism-including anair intake duct having a rotatable throttle valve mounted therein and anidle fuel discharge jet adjacent said valve, throttle valve controllinlo age including an accelerator pedal for moving said throttle valvefrom engine idle to full throttle, adjustable stop means for saidthrottle valve operatively connected with said linkage to permit firstand'second zero throttle valve positions, engine throttle position anddeceleration re- -4. 'Means for'inteiruptingthe fuel supply to aninternal combustion engine during closed throttle deceleration periods,said means includinga movable throttle valve and a fuel idle supply jetand linkage actuated by an acce'leratorpedal for controllingmovement ofsai'dv-alve 'and sponsive means connected with and controlling said stopmeans, said valve being rotatable by said linkage to said first positionupstream of said jet to idle said engine at zero throttle and to saidsecond position downstream of said jet to interrupt fuel deliveredthrough said jet when the engine is decelerating at zero throttle, saidthrottle valve having asmaller cross section area than said duet.

8. A fuel supply interruption mechanism for an internal combustionengine, said mechanism comprising a device including a motor connectedto the engine intake manifold and responsive only to an intake vacuumgreater than that vacuum obtained under normal engine idle conditionsand an air intake duct having an idle fuel discharge. jet and a throttlevalve therein, said device having a cam interconnected with an'dmovableby said motor and operativcly connected with said throttle valve andlimiting movement of said throttle valve to a-predetermined idleposition during normal engine idle conditions and moved by said motorand permitting movement'of said valve beyond said idle position whensaid greater intake vacuum is obtained whereby the fuel supply from saidjet to the engine is interrupted.

9. In a fuel supply control mechanism for an internal combustion enginehaving a throttle valve and an engine air intake controlled by saidvalve and an engine idle fuel supply jet discharging fuel into said'airintake and throttle valve control means, limiting cam meansengageablerwith said throttle valve control means and adjustable tolimit said throttle valve to idle position at zero throttle and topermit additional movement of said throttle, valve beyond idle positionat zero throttle to cut off the fuel supply from said idle jetduringzero throttle deceleration of said engine, said limitingcam meansincluding a movable cam engageable by said 'throttlevalve control meansand a vacuum energized motor for moving said cam to permit saidadditional throttle valve movement, said motor including :a return sp ig and having means. interconn c ing turn spring preventing energizationof said motor except during engine zero throttle deceleration.

10. Throttle cut-ofi and return mechanism for an internal combustionengine having a throttle valve and an engine air intake with enginevacuum imposed therein downstream of said valve and a fuel supply jet insaid intake at said throttle valve and control means for said throttlevalve including the valve rotating cam operatively connected with saidvalve and a cam actuating link and a vacuum motor connected therewithand energizable to rotate said cam through said link in one directionduring zero throttle deceleration of said engine and a return springacting on said cam to rotate said cam in the other direction uponcessation of the zero throttle deceleration condition and a vacuum lineconnected with said engine intake on said motor and imposing enginevacuum on said motor to oppose said return spring, said engine vacuumenergizing said motor to overcome said spring only during 20 zerothrottle deceleration of said engine and rotating said throttle valvedownstream of said idle jet to cut ofi fuel being delivered therefrom tosaid engine, said valve remaining upstream of said idle jet during allother engine operating conditions.

11. The mechanism of claim 10 further comprising a fuel pump havingmeans for discharging the fuel therefrom into said engine and linkageoperatively connecting said motor and said pump and moved by said motorto actuate said pump upon cessation of said engine zero throttledeceleration condition, said pump then discharging fuel into saidengine.

2,036,192 2,665,891 Smitley Jan. 12, 1954 2,762,235

Olson et al. Sept. 11, 1956

